Stroke is the 4th leading cause of US mortality and 3rd among African Americans, with African Americans exhibiting more than twice the risk of Whites. The underlying causes of racial disparities in stroke are unclear. Few studies have systematically evaluated how racial disparities in stroke might vary by socioeconomic and behavior risk factors (e.g. measures of socioeconomic status [SES], adiposity, physical activity and alcohol) and they might explain the observed disparities through their roles as intermediates in the causal pathway between race and stroke. There has been a paucity of research on the impact of socioeconomic and behavioral risk factors in stroke risk prediction. Moreover, validation of existing stroke prediction scores among African Americans is urgently needed. This innovative project will address these gaps in the literature by: (1) determining whether racial disparities in stroke and the associations of selected stroke risk factors by race are comparable in two biracial socioeconomically heterogeneous populations, (2) determining whether mediation by socioeconomic and behavioral stroke risk factors account for racial disparities in stroke beyond traditional stroke risk factors using conventional and causal frameworks, and (3) examining whether race-specific stroke prediction models improve the predictive performance (calibration and discrimination) of long-term stroke risk compared to existing stroke prediction models. These aims will be accomplished through the use of three multi-racial, well-established NIH-funded cohorts; the Women's Health Initiative, Southern Community Cohort Study (SCCS) and Reasons for Geographic and Racial Differences in Stroke. A comprehensive approach to examining racial disparities will be utilized. Novel causal mediation analyses will complement conventional epidemiologic methods and move the field forward. Furthermore, race-specific stroke prediction models will enable the development of improved prevention strategies among at-risk individuals. These socioeconomic and behavioral stroke risk factors are often routinely collected in the clinic or could be obtained at minimal cost. This grant will generate new knowledge and crucial training for my advancement to become an independent epidemiologist in the field of racial/ethnic disparities in cardiovascular disease (CVD) by developing my expertise in (1) racial disparities and social determinant of CVD; (2) statistical training in mediation analyses; (3) methodologic training in prediction modeling; (4) data management and analytic skills with Medicare claims data (CMS) for stroke ascertainment in SCCS and (5) pilot medical record collection for stroke validation in SCCS. The advanced training, mentorship and protected time provided by this career development award will provide the skills and experience necessary for conducting the highest quality racial/ethnic cardiovascular disparities research and a strong foundation for success as an independent epidemiologic racial/disparities investigator.